The Short Answer: Attics, Walls, and Anywhere Moisture Isn't a Factor

Open-cell spray foam is the right choice for interior walls, attics, cathedral ceilings, and above-grade applications where moisture exposure is low and a complete air seal is the primary goal. It delivers the same airtight seal as closed-cell foam at a lower cost per square foot — making it the smart choice for large interior areas.

At Seal Tech Insulation, we help homeowners in Brighton, Howell, and Milford choose the right foam for every part of their home. The decision between open-cell and closed-cell isn't complicated once you understand where each one excels. For Michigan building code requirements, see the Michigan Bureau of Construction Codes and Energy Star's Seal & Insulate guidelines.

What Is Open-Cell Spray Foam and How Does It Work?

Open-cell spray foam is a two-component polyurethane foam that expands dramatically when sprayed — up to 100 times its liquid volume. Unlike closed-cell foam, the cells in open-cell foam are intentionally left "open," giving the cured foam a soft, spongy texture similar to a dense foam pillow.

This open structure has two important consequences: it makes the foam vapor-permeable (moisture can pass through it slowly), and it makes the foam an excellent sound absorber. Open-cell spray foam typically achieves R-3.5 to R-3.8 per inch, compared to R-6 to R-7 per inch for closed-cell.

Despite its lower R-value per inch, open-cell spray foam creates the same complete air seal as closed-cell — and air sealing is responsible for 40% of a home's heat loss. That's why open-cell spray foam in an attic or wall cavity dramatically outperforms fiberglass batts, even though fiberglass has a higher R-value per inch on paper.

Open-Cell vs. Closed-Cell: Which Is Right for Each Location?

The Sound Control Advantage of Open-Cell Spray Foam

One of the most underrated benefits of open-cell spray foam is its superior sound dampening performance. The soft, spongy cell structure absorbs sound waves rather than reflecting them — making open-cell spray foam significantly better than closed-cell for noise reduction between rooms.

For Brighton homeowners building a home theater, a music room, a nursery, or simply wanting quieter bedrooms, open-cell spray foam in the interior walls delivers a noticeable difference. It's also commonly used in floor cavities between stories to reduce impact noise and airborne sound transmission.

Closed-cell spray foam, while excellent for exterior applications, is too rigid and dense to absorb sound effectively. For interior sound control, open-cell is always the better choice.

How Much Open-Cell Spray Foam Do You Need?

The amount of open-cell spray foam needed depends on the application and the R-value required by Michigan's energy code. Here are the most common thicknesses for Brighton-area homes:

Is Open-Cell Spray Foam Worth the Cost?

Open-cell spray foam typically costs $1.00 to $1.50 per board foot installed — roughly 30–50% less than closed-cell spray foam. For large applications like attics and cathedral ceilings, this cost difference is significant. A full attic insulation job that might cost $8,000–$10,000 with closed-cell can often be done with open-cell for $4,000–$6,000 — with the same complete air seal result.

The key is using the right foam in the right place. Open-cell in an attic is an excellent investment. Open-cell in a crawl space is a costly mistake. Seal Tech's free evaluation helps Brighton homeowners make the right choice for every part of their home before a single dollar is spent.

Seal Tech Serves Brighton & All of Southeast Michigan

Seal Tech Insulation installs open-cell and closed-cell spray foam insulation for homeowners in Brighton, Howell, Milford, and across Southeast Michigan. We serve: